Rotary apparatus for the heating of particulate or granular materials, especially stones for road-making materials



Jan. 16, 1968 A. NIELSEN 3,363, 8

ROTARY APPARATUS FOR THE HEATING OF PARTICULATE OR GRANULAR MATERIALS,ESPECIALLY STONES FOR ROAD'MAKING MATERIALS Filed April 25, 1966 Fl-G.1

United States Patent 3,363,888 ROTARY APPARATUS FOR THE HEATING OFPARTICULATE GR GRANULAR MATERIALS, ESPECIALLY STONES FOR ROAD MAKHNGMATERIALS Aage Nielsen, Copenhagen, Denmark, assignor to H. Nielsen &Son Maskinfahrik A/S, Copenhagen, Denmark, a company of Denmark FiledApr. 25, W66, Ser. No. 545,002 Claims priority, application Denmark, May3, 1965, 2

5 Claims. Zci. 263-33) ABSTRACT OF THE DISCLOSURE This invention relatesto an apparatus for heating particulate or granular materials, such asstones for roadmaking materials, and comprising a rotatably supporteddrum having at least one feed opening and one discharge opening for thematerial, means for heating material located within the drum and drivingmeans for rotating the drum about a longitudinal axis thereof.

A known apparatus of this type comprises a stationary feed funnelconnecting into a feed opening in one end wall of the drum whilst astationary discharge chute is provided in a discharge opening in theother end wall. The chute can be tilted on a horizontal axis between aninoperative position wherein it is upwardly inclined as seen from thedrum, and a discharge position wherein it is downwardly inclined. In thelatter position the portion of the chute disposed inside the drum mayoperate as a scraping member which catches the material conveyed alongthe walls of the drum during the rotation thereof and discharges it fromthe drum.

In this known apparatus it is often extremely diificult to ensurecomplete emptying of the drum after the termination of a heatingoperation as at least a few stones are very likely to remain in the drumwithout being caught by the chute unless it remains in the dischargeposition for an extended period. After the termination of the heating ofa batch of material, it is often desired to change to the treatment of abatch of a different grain size or grading, for example, in conjunctionwith the production of bituminous road building materials of diiferingcomposition or fineness, and in such case it is an obvious disadvantagethat the fresh batch may contain stones of quite a different grain size.

It is an object of the invention to provide an apparatus in which thisdisadvantage is obviated. According to the invention an apparatus of thekind referred to comprises a drum having a circumferential wall and atleast one end well, said discharge opening or openings being located insaid circumferential wall of the drum, bafile means located alongopposed edge portions of each discharge opening at the inner side andthe outer side, respectively, of said circumferential wall and extendingfrom said edge portions in opposite directions circumferentially acrossand past said opening in spaced relation 3,363,888 Patented Jan. 16,1968 to said wall, and the driving means for rotating the drum arearranged for selectively reversing the direction of r0- tation of thedrum.

The said bafile means define, in conjunction with each dischargeopening, a tortuous channel between the inner side and the outer side ofthe circumferential drum wall, and through this channel the material maybe rapidly discharged from the drum during the rotation thereof wherebythe leading edge, as viewed in the direction of rotation, of theinternal baflle means contributes to scraping the material oif the drumwall. When the drum rotates in the opposite direction, there will be notendency for the material to escape from the drum through the channelwhich, on the contrary, will operate to return to the interior of thedrum any material that might have entered the channel. Thus, withextremely simple structural and control means it has been made possibleto rapidly empty the drum completely of its contents simply by reversingits direction of rotation.

Each discharge opening may be substantially rectangular in plan view anddefined by two axially extending edges and two circumferentiallyextending edges, and the radial spacing between the drum wall and thebafile means may be substantially equal to the dimension of the openingin the circumferential direction of the drum, whereby the cross sectionof the channel referred to above becomes substantially constant over theentire length of the channel.

The invention will be explained in more detail below with reference tothe accompanying diagrammatical drawings, wherein FIG. 1 is a verticalsection, taken on line II in FIG. 2, through an apparatus embodying theinvention, wherein such parts as are not deemed necessary for understanding the invention, have been omitted, and

FIG. 2 is a section taken on line II-II in FIG. 1.

The apparatus shown in the drawings comprises a drum 1 thecircumferential wall of which consists of a cylindrical central portion2 and two conical end portions 3. One end wall 4 of the drum is providedwith a central opening 6, and a stationary disposed feed funnel 7, thesupport means of which is not shown, extends some distance into the drumthrough the opening 6. The other end wall 5 of the drum is provided witha central opening 8, and a diagrammatically shown oil burner 9 is, in amanner not shown, supported outside the drum the contents of which areheated by means of the burner flame during operation of the apparatus.

To each end portion 3 of the drum there is secured, for example bywelding, a cylindrical ring 10 co-axial with the drum axis, and therings 10 engage driving wheels 11 as well as supporting means, notshown, for rotatably supporting the drum. The driving rollers 11 whichmay be coated with a friction-increasing material, such as rubber, aredriven by means of reversible electric motors 12.

The central portion 2 of the drum 1 is surrounded by a stationary jacket13 which beneath the middle portion of the drum has a discharge channel14, and which diametrically opposite said channel 14 has a flue 15 forremoving hot gases from the drum.

In the cylindrical central portion 2 of the drum there are provided aplurality, in the example shown there are six, of discharge openings 16of substantially rectangular shape. In the longitudinal direction of thedrum the openings 16 extend over the major part of the length of thecentral portion 2. At the inner side and outer side, respectively, ofthe central portion 2 of the drum a baflie or guide member in the shapeof a vane 17 or 18, respectively, is associated with each opening 16.The vane 17 is secured, for example by Welding, to the inner wall of thedrum portion 2 along one longitudinal edge of the opening 16 and thenceit extends first in an inclined direc tion towards the interior of thedrum, see FIG. 2, and then substantially tangentially, i.e. parallel tothe drum wall, across the opening 16 and past the opposite edge thereof.Similarly, the vane 18 is secured to the opposite axial or longitudinaledge of the opening 16 and extends first in an outwards inclineddirection from said edge and then parallel to the drum wall across andpast the opening 16. As shown, the radial distance between each of thevanes and the associated part of the drum wall is by and large equal tothe tangential width of the opening 16. As shown, each vane 17 or 18covers a portion of the circumference of the drum section which issubstantially equal to half the distance between two successive openings16. With a view to stiffening the vanes 17 and 18 they may, as shown, beconnected with the drum wall along their axial edges by means of wallportions 19 and 2.0 respectively.

The drum shown may, for example, be used for heating and drying stonematerial for road surfaces. A weighedoff portion of stones, pre-gradedas requested, is fed to the drum through the funnel 7, and then the drumis caused to rotate by starting the motors 12, and the oil burner 9 isignited. When the material has remained in the drum for a length of timesufiicient for freeing the material of water and for heating it to adesired temperature, which for example may lie between about 70 and 200deg. centigrade, it is discharged from the drum through the dischargechannel 14 and passed on to for example a mixer, not shown, in which thestones are coated and mixed with asphalt or another bituminous binder.In the apparatus described this discharge operation is carried outsimply by reversing the direction of rotation of the drum 1.

During the heating of the material, the drum rotates in the direction ofarrow A, FIG. 2, and the material contained in the drum will then beincapable of leaving the drum through the channels formed by theopenings 16 and the adjoining passages between the drum wall and thevanes 17 and 18, while the hot gases may escape freely through thechannels located above the surface of the material layer and bedischarged through the flue 15. When the direction of rotation isreversed, so that the drum rotates in the direction of arrow B, thematerial will be capable of flowing rapidly out of the drum through saidchannels. In such case, the vanes 17 operate as guide members whichinitially scrape the material oif the drum wall and subsequently guideany remaining stones, into the channels. Due to the conical shape of thedrum ends 3, the material at the drum ends will quickly find its way tothe central portion 2 as soon as the material originally contained inthis section of the drum has been discharged through the opening 16.Thus, a rapid and total removal of all material from the drum isattained solely by reversing the direction of rotation of said drum.Consequently, it is also possible without risking unwanted mixing ofdifferent materials or without operational interruption for the purposeof separately cleaning the drum, to successively treat charges ofmutually widely difiering materials.

What I claim is:

1. Apparatus for heating particulate or granular materials, such asstones for road-making materials, comprising a drum having at least oneend wall and a circumferential wall having a cylindrical central portionand two conical end portions; means for rotatably supporting said drum;means for rotating said drum about its longitudinal axis and forselectively reversing the direction of rotation of the drum; at leastone feed opening for introducing material into said drum; at least onedischarge opening located in said central wall portion; baflle meanslocated along opposed edge portions of said discharge opening at theinner side and the outer side, respectively, of said circumferentialwall and extending from said edge portions in opposite directionscircumferentially across and past said discharge opening in spacedrelation to said wall; and means for heating material located withinsaid drum.

2. Apparatus as claimed in claim 1, wherein said discharge opening issubstantially rectangular in plan view and defined by two axiallyextending edges and two circumferentially extending edges, and theradial spacing between said circumferential drum wall and said bafllemeans is substantially equal to the dimension of said opening in thecircumferential direction.

3. Apparatus as claimed in claim 1 and comprising a plurality ofdischarge openings in said circumferential wall, wherein the dimensionsof each bafile means in the circumferential direction of the drum issubstantially equal to one half of the distance between adjacentdischarge openings in said wall.

4. Apparatus as claimed in claim 1, wherein said means for rotating saiddrum comprise reversible electric motors.

5. Apparatus as claimed in claim 1, further comprising a stationaryjacket surrounding said central wall portion and adjoining parts of saidconical end portions of said circumferential drum wall, a dischargechannel opening in the lower middle portion of said jacket, and a gasexhaust conduit extending from the upper middle portion of said jacket.

References Cited UNITED STATES PATENTS 3/1943 Smith 21418 2/1960Schoonover 263-33

